1. Field of the Invention
The present invention is directed to a transport system for a remote inspection device and more particularly, to a transport system which will move an inspection device into a portion of a nuclear steam generator and allow the inspection device to be driven and manipulated once it is inside.
2. Description of the Related Art
An operating nuclear steam generator is constantly transferring heat from a heat source fluid to a drive fluid such as water converted into steam to drive a steam turbine.
The fluid from the heat source enters the steam generator, illustrated in FIG. 1, and passes through U-shaped tubes grouped in a tube bundle 12. The tube bundle 12 is surrounded by a tube wrapper 14 and then by a steam generator shell 16. A space exists between the tube wrapper 14 and the outer shell 16. Impurities in the drive fluid can be deposited as sludge at the bottom of the tube bundle 12 below the tube wrapper 14 during operation. In addition, objects lost during steam generator construction, such as welding rods, can become dislodged and fall through the annulus formed between the tube wrapper 14 and the outer shell 16 which is approximately 2 to 3 inches wide. It is necessary during periodic inspections to inspect the 4 to 6 inch cavity around the tube bundle 12 and below the tube wrapper 14 because the foreign objects create a threat to the integrity of the tube bundle 12 and, as a result, are removed, if possible. The only access into the space between the tube wrapper 14 and the outer shell 16 are handholes 18 approximately 5-6 inches in diameter and approximately 12-24 inches above a tube sheet through which the tubes pass. It is difficult to insert an inspection device, such as a miniature camera, etc., into the 2 to 3 inch space between the tube wrapper 14 and outer shell 16, and then guide the camera around the bottom periphery of the tube bundle for inspection purposes. The end of the inspection device can also include manipulation devices such as a gripper which will allow foreign objects in the cavity to be removed. The source fluid passing through the tube bundle 12 carries radioactive contaminants and human exposure to the small amount of the radiation passing through the handholes 18 must be kept at a minimum. Devices which require manipulation by a human through the handhole for inspecting the cavity around the bottom of the tube bundle thus have serious disadvantages.